Here are a couple of concrete examples to add to the "nopes". Suppose you take off at a steep angle. With fpv you see the sky. What is the actual angle of the plane? You can't tell.

Or picture making a turn. You bank the plane and give some up. In the turn, are you climbing, descending, or maintaining level flight? Hard to tell on fpv, except for extremes. Even worse would be trying to detect adverse yaw.

If you've flown heli's I'm sure you can learn to fly fixed wing pretty quickly. Add fpv when you're proficient.